Air Pollution Could Shrivel Sperm’s DNA

As if the damage of foul air to our lungs wasn’t bad enough, scientists have found another way for smog to harm people: by wreaking genetic havoc in men’s sperm.

In a study published Monday in the Proceedings of the National Academy of Sciences, a team of Canadian geneticists put open-air cages of male mice downwind of steel mills and beside a highway. A second group of mice were placed beside them in cages outfitted with air purifiers.

After a couple months, the researchers compared the mice. Sperm from the industrial group, they found, had half again as many genetic mutations as sperm from HEPA-breathing counterparts. The polluted sperm was also hypermethylated, meaning that genes were being turned on and turned up more than they should have been.

Though mice aren’t people, the findings do point to a plausible mechanism by which air pollution could affect humans. Mutations in so-called germline
DNA "may cause population-level changes in genetic composition and disease," the researchers wrote. "Changes in methylation can have widespread repercussions for chromatin structure, gene expression and genome stability. Potential health effects warrant extensive further investigation."

The paper comes out at an opportune time: while President Bush’s 2003
Clear Skies Act died in committee, individual provisions were later enacted. These slowed — even reversed — a federal crackdown on power plant pollution, and the Bush Administration was criticized forignoring studies it commissioned on the dangers of failing to reduce mercury pollution. Meanwhile, the Environmental Protection Agency has been involved in a running battle over its sometimes-weak clean air enforcement.

Clean air takes on even more significance if it becomes an issue of genetic health. One possible line of questioning: could rising pollution levels cause the sort of sperm mutations recently identified in parents of some children with autism? I sent the question to the researchers from this study, and will let you know what they say.

Here’s The Thing With Ad Blockers

We get it: Ads aren’t what you’re here for. But ads help us keep the lights on. So, add us to your ad blocker’s whitelist or pay $1 per week for an ad-free version of WIRED. Either way, you are supporting our journalism. We’d really appreciate it.